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SSL/TLS Security Guide

Master SSL/TLS security including certificate analysis, HTTPS implementation, security headers, and TLS configuration best practices

Table of Contents

SSL/TLS Basics

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that provide secure communication over a computer network.

Protocol Versions

SSL 1.0 & 2.0

Deprecated and insecure. Should never be used.

SSL 3.0

Deprecated due to POODLE vulnerability. Not recommended.

TLS 1.0

Legacy protocol. Considered weak and should be disabled.

TLS 1.1

Legacy protocol. Considered weak and should be disabled.

TLS 1.2

Widely supported and secure. Minimum recommended version.

TLS 1.3

Latest version with improved security and performance.

How SSL/TLS Works

  1. Client Hello: Client initiates connection and sends supported cipher suites
  2. Server Hello: Server responds with chosen cipher suite and certificate
  3. Certificate Verification: Client verifies server's certificate
  4. Key Exchange: Client and server exchange encryption keys
  5. Handshake Complete: Secure communication begins

Certificate Analysis

SSL/TLS certificates are digital documents that verify the identity of a website and enable encrypted connections.

Certificate Components

Subject

Entity the certificate is issued to (domain name, organization)

Issuer

Certificate Authority (CA) that issued the certificate

Validity Period

Start and end dates when certificate is valid

Public Key

Public key used for encryption and verification

Digital Signature

CA's signature proving certificate authenticity

Extensions

Additional information (SAN, key usage, etc.)

Certificate Types

TypeValidationUse CaseTrust Level
DV (Domain Validated)Domain ownership onlyPersonal websites, blogsBasic
OV (Organization Validated)Domain + organization verificationBusiness websitesMedium
EV (Extended Validation)Comprehensive verificationE-commerce, bankingHigh

Security Headers

HTTP security headers provide additional layers of protection against various web vulnerabilities and attacks.

Essential Security Headers

Strict-Transport-Security (HSTS)

Forces browsers to use HTTPS connections only.

Strict-Transport-Security: max-age=31536000; includeSubDomains

Content-Security-Policy (CSP)

Prevents XSS attacks by controlling resource loading.

Content-Security-Policy: default-src 'self'; script-src 'self'

X-Frame-Options

Prevents clickjacking attacks by controlling framing.

X-Frame-Options: DENY

X-Content-Type-Options

Prevents MIME type sniffing attacks.

X-Content-Type-Options: nosniff

Referrer-Policy

Controls referrer information sent with requests.

Referrer-Policy: strict-origin-when-cross-origin

TLS Configuration

Proper TLS configuration is crucial for maintaining security while ensuring compatibility with clients.

Cipher Suites

Recommended Cipher Suites

  • • TLS_AES_256_GCM_SHA384 (TLS 1.3)
  • • TLS_AES_128_GCM_SHA256 (TLS 1.3)
  • • ECDHE-RSA-AES256-GCM-SHA384 (TLS 1.2)
  • • ECDHE-RSA-AES128-GCM-SHA256 (TLS 1.2)

Avoid These Cipher Suites

  • • RC4-based ciphers (weak encryption)
  • • DES and 3DES (outdated)
  • • NULL ciphers (no encryption)
  • • Export-grade ciphers (intentionally weak)

TLS Configuration Best Practices

Protocol Configuration

  • Enable TLS 1.2 and TLS 1.3 only
  • Disable SSL 2.0, SSL 3.0, TLS 1.0, TLS 1.1
  • Use strong cipher suites only
  • Enable perfect forward secrecy

Certificate Management

  • Use certificates from trusted CAs
  • Monitor certificate expiration
  • Implement certificate pinning
  • Use OCSP stapling

Common SSL/TLS Vulnerabilities

High Severity

Heartbleed (CVE-2014-0160)

Memory leak in OpenSSL allowing private key extraction

POODLE (CVE-2014-3566)

Padding oracle attack on SSL 3.0

DROWN (CVE-2016-0800)

Attack using SSL 2.0 servers to break TLS

Medium Severity

BEAST (CVE-2011-3389)

CBC mode vulnerability in TLS 1.0

CRIME (CVE-2012-4929)

Compression ratio info-leak made easy

FREAK (CVE-2015-0204)

Factoring attack on RSA-EXPORT keys

SSL/TLS Best Practices

Implementation

  • Use TLS 1.2 or higher only
  • Implement HSTS with long max-age
  • Use strong cipher suites only
  • Enable perfect forward secrecy
  • Implement proper security headers

Monitoring & Maintenance

  • Monitor certificate expiration
  • Regular security assessments
  • Keep software updated
  • Use automated monitoring tools
  • Test configuration regularly

SSL/TLS Security Tools

Use our specialized SSL/TLS tools to analyze certificates, check security headers, and assess your HTTPS implementation:

SSL Certificate Analyzer

Check SSL/TLS certificate validity, expiration, and security configuration.

Try SSL Analyzer →

Security Headers Checker

Analyze HTTP security headers and get detailed security recommendations.

Try Headers Checker →

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